The present invention relates to a novel rifamycin derivative or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective component. More particularly, the present invention relates to a novel rifamycin derivative having the formula (I): ##STR4## wherein R.sup.1 is hydrogen atom, methyl group or ethyl group, R.sup.2 is an alkyl group having 1 to 4 carbon atoms, and A is a group having the formula: ##STR5## in which n is an integer of 3 to 5, or a group having the formula: ##STR6## in which R.sup.3 is an alkyl group having 1 to 5 carbon atoms, or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective ingredient.
The rifamycin derivative of the present invention is a novel compound which has not yet been reported in the literature.
For the purpose of developing a novel superior antibacterial agent, the present inventors have synthesized a novel rifamycin derivative having the formula (I): ##STR7## wherein R.sup.1, R.sup.2 and A are as defined above and investigated the antibacterial activity and pharmacological characteristics thereof, and as a result, found that the novel rifamycin derivative having the formula (I) exhibits a strong antibacterial activity and excellent pharmacological characteristics.